Power transfer efficiency analysis of U-WPT system

In order to improve the power transfer efficiency and ensure the space cleanliness of power transfer direction in inductive coupled wireless power transfer (WPT) system, this paper proposed a U-WPT system structure. Based on mutual inductance coupling theory, this paper derived the analytic function of power transfer efficiency. By contrasting U-WPT system and traditional two coils system, we drew the condition of improving the power transfer efficiency. With special examples of U-WPT system, we discussed the impact of turns and location of intermediate resonant coil to the power transfer efficiency. The experimental result shows: subject to the condition of power transfer efficiency improvement, by designing reasonable intermediate coils, the power transfer efficiency can be increased from 8.27% to 74.83%, and the power transfer direction's space is cleaner. The result shows that U-WPT system can effectively improve the power transfer efficiency in ensuring the cleanliness of the space situation.